You will like the RR gun. They are a good outfit to deal with.
My bullseye guns have slide mounts because I find them simpler for disassembly and cleaning. The high masters in my area shoot slide mounts. Most bullseye shooters I see use slide mounts.
I find that it's easier to cycle the action with a gun that has a frame mount.
RR is pretty good about tuning the gun so that it will cycle with a typical ~3.9grain of bullseye powder charge. If it does need more powder than that, it will only be one or two tenths of a grain more, which has no practical effect on recoil or blast.
Talk to RR and ask them:
1) How do the cleaning and disasembly procedures differ
2) How does recoil differ? I expect the slide mount's recoil to have more duration than a frame mount gun, but I don't know for sure.
If I were buying another bullseye gun I'd probably try a frame mount because they have improved over the years. The trend by builders seems to be in that direction. Up until fairly recently I don't think RR offered a frame mount wad gun. But I really have no complaints about the slide mount. Action pistol shooters almost universally use the frame mount. Why? There must be a speed advantage of some kind. If you can get a speed advantage in a wad gun, then it may help your rapid fire scores.
Before buying, subscribe to the bullseye forum at
http://www.lava.net/~perrone/bullseye/ and post your question there. You can count on a good answer from people who have used both styles extensively.
